Short History of the T-34, Part 1 (1937-1942)
Introduction Picture: T-34-85 tank on display at Musée des Blindés in April 2007. The T-34 was a Soviet medium tank that had a profound and lasting effect on the field of tank design. Although its armour and armament were surpassed later in the war, it has been often credited as the most effective, efficient, and influential tank design of World War II. At its introduction, the T-34 possessed an unprecedented combination of firepower, mobility, protection, and ruggedness. Its 76.2 mm high-velocity tank gun provided a substantial increase in firepower over any of the T-34's contemporaries and its heavy sloped armour was difficult to penetrate by most contemporary anti-tank weapons. It had a powerful diesel V12 engine, less sensitive than high-octane petrol engines, both to increase range and to avoid bursting in flames too easily, as the BT-5 and BT-7 did during the war against Japan in Manchuria. In 1939, the most numerous Soviet tank models were the T-26 infantry tank and the BT series of fast tanks. The T-26 was slow-moving, designed to keep pace with infantry on the ground, and the BT tanks were cavalry tanks: fast-moving and light, designed for manoeuvre warfare. Unfortunately, they were insufficient against the enemies the Soviet Union had to face, so a team lead by engineers Mikhail Koshkin and Alexander Alexandrovich Morozov was assigned in 1937 to design a replacement for them at the Kharkiv Komintern Locomotive Plant (KhPZ). This was to be a better, "universal tank". T-34's grandparents Picture: the BT-SV, one of the grandfathers of the T-34. The T-34 lineage can be traced back to the Christie tank. This tank was associated with the suspension system that was the backbone of the Russian light tank industry from 1936. The BT series was upgraded to the extent that the last BT-IS prototype, itself derived from the successful BT-7, was nearly a medium tank rather than a light scout tank. The A-20, the next tank in the line, combined the chassis and suspension of the BT-IS with a new turret and the sloped armour tested on the BT-SV (1936). The BT-IS and BT-SV/2 had been the most noteworthy programs aimed at improving the BT series, with the SV's key innovation being the sloped 25mm armour whose steep angles increased effective thickness and protective qualities against typical anti-tank projectiles. A-20, T-34's first dad Picture: A-20, from morozovkmdb.com. By the end of 1937, planners at GABTU (Main Automotive-Armoured Tank Directorate of the Ministry of Defence of the Soviet Union) began to realize that merely building improved variants of the T-26 and BT-7 would not solve the Soviet armour deficiencies. Even the improved versions still were thinly armoured and undergunned vehicles that would soon be obsolete, so they needed a completely new tank design. Thus, in November 1937, GABTU ordered KhPZ to begin design work on a new medium tank and the Voroshilov and Kirov factories in Leningrad a new heavy tank. The new medium tank was designated A-20. It had the new Model V-2-34 engine that used less-flammable diesel fuel in a V12 configuration designed by Konstantin Chelpan, but still showed very conservative thinking, at 20 tons, with a 45mm gun, 20mm of armour and a wheel-track system. Wheel-track system on the BT series and the A-20 Picture: BT series tanks and the A-20. The wheel-track system was a feature designed by J. Walter Christie to reduce wear of the unreliable tank tracks of the 1930s. In about thirty minutes, the crew could remove the tracks and engage a chain drive to the rearmost road wheel on each side, allowing the tank to travel at very high speeds on roads. The A-20's 8×6 wheel convertible drive was similar to the BT tank's 8×2 and allowed it to run on wheels without caterpillar tracks. This feature had greatly saved on maintenance and repair of early Soviet tank tracks, and allowed the high road speeds, but gave no advantage in combat and its complexity made it difficult to maintain. Extra info: Notice in the pictures above the similar road-wheels. All Soviet wheel-track system tanks had rubberized wheels, a feature not unique to wheel-track tanks, but vital for them in order to provide traction on roads. According to "Russian Tanks of World War II Stalin's Armored Might", by Tim Bean & Will Fowler, 2002, and "Russian Tanks and Armored Vehicles 1917-1945," by Wolfgang Fleischer, 1999, the BT-7M (aka BT-8) could reach a top speed of 86 mph (more than 138 kmph) and the BT-7-2 (1937) 72 mph (almost 116 kmph). The BT-IS had a top speed of 70 mph (more than 112 kmph), according to "Russian Armour Volume 2: Light Tank T-27, T-38, BT, T-26, T-40, T-50, T-60, T-70," by Mikhail Baryatinskiy, 2006. A-32, the next step towards scaring the shit out of the Germans Picture: A-32, from Robert Forczyk, Panther Vs T-34: Ukraine 1943. 2007. p. 19. In 1938, it was decided that the A-20 was still vulnerable to German guns, so KhPZ was ordered to develop a variant known as the A-30, with 30mm armour and a 76.2mm gun. Koshkin didn't like the wheel-tracked system used on the A-20 because by 1938 track design improvements rendered it a waste of space, weight, and maintenance resources, despite the road speed advantage. He started working on a tracked-only variant known as the A-32 or T-32, named after its 32mm of frontal armour. It had an L-10 76.2mm gun, and the same Model V-2-34 diesel engine. General Pavlov, head of GABTU, liked the operational mobility the wheel-tracked system offered and insisted on their development, so by summer 1938, KhPZ had three new medium tanks prototypes in various stages of development: the A-20, the A-30 and the A-32. In August 1938, Josef Stalin was at a conference on new tank designs in Moscow, where he took a personal interest in the medium tank prototypes and was convinced by Koshkin that the tracked A-32's better armour and off-road mobility made it the best choice. The last nail in the A-30 project's coffin was Koshkin's mention that the 76.2mm gun would not fit in the A-30's small turret, when Stalin halted the project. Unfortunately, the A-32 was opposed by Defence Commissar Klimenti Voroshilov, whose son-in-law, Zhosif Kotin, worked on the development of the KV heavy tank series in Leningrad. Voroshilov and Kotin didn't like the competition, so Voroshilov pressed ahead the development of the A-20, but Koshkin still developed the tracked-only A-32. When the A-20 and A-32 were completed and sent to Kubinka for evaluation, despite General's Pavlov preference for the A-20, the A-32 had equal mobility, but clearly superior armour and firepower. The only reason Stalin didn't make a decision in favour of the A-32 right away was that he wanted a cheap tank to mass produce, not another T-28 or T-35 that could only be built in token numbers. The decision was left floating in bureaucratic limbo for several months, pending more testing. Weight tests on the A-32 determined that: "It is reasonable to produce experimental vehicles based on the A-32 tank with increased weight to 24 tons due to thicker armour." For more details about the weight tests, visit: http://tankarchives.blogspot.de/2015/09/t-34-prototype-testing.html. For details about the A-20 and A-32 tests at Kubinka, visit: http://tankarchives.blogspot.de/2015/08/a-20-and-32-trials.html. A-34, the final step Picture: A-34, from morozovkmdb.com. On November 30, 1939, the Soviet Union attacked Finland, but lost 80 tanks in the first week to a handful of Finnish AT guns, and the Soviet 45mm gun proved completely ineffective at neutralizing Finnish bunkers, so the A-32 was finally accepted. Despite this apparent victory, Koshkin's latest version of the tank, later named A-34 by Koshkin after the year 1934, when he began to formulate his ideas about the new tank, and to commemorate that year's decree expanding the armoured force and appointing Sergo Ordzhonikidze to head tank production, was not approved by Voroshilov. It was 38% heavier than the A-32, had wider tracks, a newer L-11 76.2mm gun and 45mm of sloped armour, which Koshkin felt would make it invulnerable to 37mm fire. Voroshilov requested further testing before approving the T-34, to buy even more time for his son-in-law. A-34, the long drive Picture: First and second A-34 prototypes, from wardrawings.be. Despite all opposition, Koshkin would not give up. In 1940, he ventured upon the dramatic demonstration of driving the first two unarmed T-34 prototypes to Moscow. Between March 5 and 17, he and two crews drove roughly 700km from Kharkov to Moskow to present the tanks to Stalin. On the road, some drivetrain shortcomings were identified and corrected, but Koshkin contracted the pneumonia that would kill him six months later. Next, the prototypes were driven to Kubinka where their armour withstood fire from 45mm AT guns and had mobility trails against a Panzer III purchased from Germany. According to Zaloga, at first, "Koshkin's design team was very worried about how their tank would compare to the Panzer III, but were relieved to find that the PzKpfW III was inferior to the T-34 in armour, firepower and mobility. It was derisively referred to as a pretty toy, over-engineered and needlessly comfortable for the crew." For details about the tests ran at Kubinka visit: http://tankarchives.blogspot.com/2015/07/t-34-protection-tests.html Ultimately, the T-34 was approved and production was scheduled to begin in June 1940. Family reunion, one final note before moving to the actual production variants Picture: BT-7M, A-20, T-34 M1940, T-34 M1941, from Anthony Tucker-Jones, T-34 The Red Army's Legendary Medium Tank. 2015. p. 16. There were two main production families of the T-34, each with subvariants, but identification the exact version is complicated. Turret castings, superficial details, and equipment differed between factories; new features were added in the middle of production runs, or retrofitted to older tanks; damaged tanks were rebuilt, sometimes with the addition of newer-model equipment and even new turrets. Some tanks had appliqué armour made of scrap steel of varying thickness welded onto the hull and turret; these tanks are called "s ekranami" (with screens), although this was never an official designation for any T-34 variant. The Red Army never had a consistent policy for naming the T-34, but academic sources like AFV expert Steven Zaloga have used Soviet-style nomenclature: T-34 for the models armed with 76.2 mm guns, and T-34-85 for models armed with 85 mm guns, with minor models distinguished by year, as T-34 Model 1940. Some Russian historians use different names: they refer to the first T-34 as the T-34 Model 1939 instead of 1940, all T-34s with the original turret and F-34 gun as Model 1941 instead of Models 1941 and 1942, and the hexagonal-turret T-34 as Model 1942 instead of 1943. German intelligence in World War II referred to the two main production families as T-34/76 and T-34/85, with subvariants receiving letter designations such as T-34/76A. When the German Wehrmacht used captured T-34s, it designated them Panzerkampfwagen T-34®, where the "r" stood for "russisch" (Russian). The Finns referred to the T-34 as the "Sotka" after the common goldeneye, because the side silhouette of the tank resembled a swimming waterfowl. The T-34-85 was called "pitkäputkinen Sotka" (long-barrelled Sotka). Moral of the story is: the way I'll break up the variants here is not set in stone. I'll personally use the variant naming that starts with Model 1940 and ends with Model 1943, rather than the preferred Russian classification. One more note: You can actually see right here the main differences between the Model 1940 and Model 1941 turrets. Note the different guns and mantlets, as well as the number of periscopes (one on the M1940, two on the M1941), but more on that later. The hatch was the same. The SPKO periscope on the hatches is a rarity, with it rarely appearing on anything else than the early M1940 models. T-34/76 Model 1940: Introduction Picture: T-34/76 Model 1940, from o5m6.de. German designation: T-34/76A. The T-34/76 model 1940 was the first production version. Full-scale production started in autumn 1940. They first saw action during Operation Barbarossa, when they performed well despite the lack of training of their crews and inept command, just like the KV-1. The Panzers couldn't match them in single combat, but there were only a handful of them, largely spread on a gigantic front. It had a complex hull that was difficult to produce. The shaped MG port, bracket for the driver's hatch and other contoured areas were initially mounted as a single piece of steel, which was difficult and time-consuming to create. Zaloga noted that this early model enjoyed a high level of craftsmanship in its manufacture that would disappear after the beginning of the war, sacrificed for ease of production. Due to a shortage of new V-2 diesel engines, the initial production run from the Gorky factory was equipped with the BT tank's MT-17 gasoline-powered engine and an inferior transmission and clutch. The first 115 tanks to roll off the factory floor were also fitted with a ball-mounted machine gun in the rear of the turret, but this feature was subsequently discarded. The T-34 had 45mm of frontal armour and 40mm on the sides. On the early models, the large disc wheels had the luxury of solid rubber tires. Radios were expensive and in short supply, so only company commanders' tanks could be fitted with radios (originally the 10-RT 26E radio set). The rest of the tank crews in each company signalled with flags. T-34/76 Model 1940: The L-11 Gun Picture: T-34/76 Model 1940, wardrawings.be. There were three contenders for the T-34's gun: the L-11, the F-32 and the F-34. The first belonged to the Kirov factory in Leningrad, and the latter two to Factory no. 92 at Gorkiy (formerly Nizhny Novgorod). Although the F-34 was the superior weapon and ready for production, Marshal Grigory Kulik's high-handed interference to ensure that his Kirov factory got the work had made the relevant bureaucrats too frightened to approve the better gun, but Vasily Garbin, head of the design bureau at Gorkiy, and A. Elyan, the plant director, still ordered the creation of a reserve stock of F-34s. The first F-34 guns were completed in January 1941 and began to appear on some T-34s in February, but the official M1941 variant was not formally approved until summer, after the outbreak of the war, when tank units in the field clamoured for more. Thus, the T-34 Model 1940 was armed with the L-11. The KV-1 Model 1939 had also used the L-11, but the 1940 model switched to the F-32 on a new mantlet. Later models were armed with the superior F-34, much to Kulik's dismay. The F-34 stayed in service until replaced by the D-5T and ZiS-S53 85mm guns on the T-34/85, but more on that later. The best way to identify the Model 1940 is by its L-11 76.2mm 30.5 calibres long gun, recognizable due to a recuperator above a barrel. Mounted low in the mantlet, it was the shortest gun the T-34/76 ever used. There were only three shorter 76.2mm tank-guns used by Soviet vehicles: the PS-3 20.6 calibres long gun on the AT-1 (artillery tank variant of the T-26), and the KT-28 16.5 calibres long and L-10 23.7 calibres long guns on the T-28. The F-32 was only 0.5 calibres longer, at 31 calibres, but the F-34/ZiS-5 ruled at 41.5 calibres. The L-11 could penetrate most German tanks from over one kilometre in June 1941. This, combined with the 45mm armour sloped at 45 degrees meant that the T-34 could effectively fight the enemy at long range with little fear of being destroyed. From the first day of Barbarossa, the Germans were shocked as their 37mm anti-tank guns couldn't penetrate the T-34's frontal armour. One account describes a German unit shooting at a T-34 23 times, with all 37mm rounds bouncing off until they finally managed to damage the turret ring and the tank retreated, otherwise unscathed. An example of poor crew training, the T-34 was unable to even hit the German anti-tank gun. Supposedly, the 37mm was called "the army's door-knocker" afterwards. T-34/76 Model 1940: The turret and the hatch Picture: T-34/76 Model 1940, from o5m6.de and inside of an early T-34 (1940 or 1941), from Steven Zaloga, Armoured Champion: The Top Tanks of World War II. 2015. The Model 1940 had a two-man turret, which meant that the commander was expected to serve as either gunner or loader (mostly gunner). The turret also had a single, large hatch with a single periscope on the left, nicknamed "pirozhok" (stuffed bun) because of its characteristic shape. Some versions of the hatch had a SPKO periscope installed on them, but on later M1940 and M1941 tanks, the periscope was not installed, making the hatch a one-piece element for ease of production. It was easy to produce, but it was very heavy and had a tendency to jam. If it jammed and the tank burst into flames, the crew would burn alive inside. The hatch also made it difficult for the commander to look outside without exposing himself, which combined with the inadequate vision devices, meant the early T-34 crews had very bad situational awareness. This combined with the lack of training for crews and command structure crippled by Stalin's purges lowered the impact the T-34 could have had. Other than the hatch, notice the very large rear exhaust covers. Tanks-encyclopedia.com stated they were new to the Model 1941, but this is a Model 1940, so unless they were retrofitted, Tanks-encyclopedia is wrong. You can see such covers on other M1940s (check the next pictures), so this one was not an exception. Also notice the rectangular transmission access hatch between the rear exhausts. More on that later. T-34/76 Model 1940: Spare transmission Picture: T-34/76 Model 1940, from o5m6.de. Due to an unreliable transmission, some tanks carried around a spare transmission attached to the back of the hull for replacement. T-34/76 Model 1940: Cast turret Picture: T-34/76 Model 1940 with cast turret, from o5m6.de. Some versions of the Model 1940 came with a cast turret rather than a welded turret, to simplify production. This turret was developed by V. Nitsenko as an alternative to the cold-rolled welded one, but was produced on a limited scale at one of the T-34 satellite plants in late spring 1941. T-34M: A project that never came to fruition Picture: T-34M, from morozovkmdb.com The original Christie suspension that was used in the T-34 was far from perfect. It offered great cross-country performance but used bulky springs that took up a lot of internal space. The KV heavy tank and T-50 infantry tank instead used a more efficient torsion bar suspension system. When the Council of People's Commissars ordered the improvement of the T-34 in May 1941, it was planned to replace the Christie suspension with the torsion bar, increase the 45mm frontal armour to 60mm, the side armour to 40mm, and the turret diameter to 160cm. A commander's cupola was to be also added to the new hexagonal, three-man turret. Other improvements included a new drivetrain, a 600HP V-2 engine, a new planetary gear transmission and internal shock absorption. The new version was labelled T-34M (factory designation A-43). 380 out of the 800 T-34Ms planned were to be equipped with the ZiS-4 gun, with 235 of them also equipped with a flamethrower to compensate for the deficiencies of the 57mm HE shell. The remaining 420 would have been equipped with the F-34, out of which 65 would have also had the flamethrower. Unfortunately, the development was abandoned when the war broke out, with only a small number partially built. T-34/76 Model 1941: Introduction Picture: T-34/76 Model 1941, from U.S. Army Ordnance Museum, Aberdeen Proving Ground, USA. German designation: T-34/76B. The next major variant of the T-34 was the T-34/76 Model 1941. Streamlined for mass production, it was easier and cheaper to build due to the new elements, including the simplified hull and gun mount. It also had increased armour on the floor and engine roof, as well as turret roof, sides and rear. The rectangular transmission hatch was replaced by a larger, circular hatch (although some tanks still had the rectangular hatch). This model started using the 9-RS radio set (also installed on the SU-100), when it was available. The tank in the picture is a model 1941 with welded turret. Along with the other T-34/76 (#674) and the KV-1 (#677) at Aberdeen Proving Ground it was presented to the museum by the Soviet Government in October 1942. T-34/76 Model 1941: A new, better gun Picture: F-34 tank gun on the T-34 Model 1941, from primeportal.net. The L-11 gun was replaced by the superior, higher-velocity F-34, as explained above. Note that there is a difference between the 76 mm tank gun M1940 F-34 and the 76 mm tank gun M1941 ZiS-5. The latter was a modified version used on the KV-1 Model 1941, designed to better fit its turret. The T-34/76 only used the F-34 model. Germans crews complained that the T-34's gun could blow off the commander's cupolas on the Pz. III and Pz. IV, proof that the armor was inadequate and the attachment faulty, as well as how accurate and powerful the Soviet gun was. On the other side, despite their skill, the Panzer crews could only take out the T-34 by shooting the rear drive-sprocket and with lucky shots on the turret ring. T-34/76 Model 1941: The turret mostly unchanged Picture: T-34 of the 116th Tank Brigade in the Volga Military District, from Steven Zaloga, Armoured Champion: The Top Tanks of World War II. 2015. Despite crew complaints about the lack of protection for the commander and small turret, command was more interested in ease of production, so little was changed. The Model 1941's turret could still only house two people. It added an additional periscope to the right, but kept the large hatch, and with it, all problems discussed about it above. The commander could operate with the hatch open while traveling, but the awkward location made it impractical to do so in combat. Interesting note: On tanks-encyclopedia.com I read that the hatch was new to the 1941 model, but from what I could gather in my research, the 1940 model had the same hatch (with the exception of the periscope). Pictures seem to confirm this; the hatches for the two models have the same shape, so unless the 1941 hatch was somehow heavier, I'd say they are the same. Another interesting note: The T-34/76 M1941 tanks at Muzeum Wojska Polskiego and Muzeum Oreza Polskiego w Kolobrzegu in Poland and the U.S. Army Ordnance Museum only have one periscope on the left side of the turret, like the Model 1940. There are several possible reasons for that. My research revealed that the periscope on the right was deleted on most T-34/76 production due to wartime shortages; this would be the most probable reason. Alternatively, the right periscope could have been removed after production, in which case there should be a hole in the turret in its place, or the turret could be from the 1940 model that was retrofitted with the new F-34 gun. Another possibility is that they are part of the batches of M1940 tanks produced in February 1941 with the new F-34 guns. Regardless, it turns out that counting the number of periscopes is not a reliable way of identifying the T-34/76 model. T-34/76 Model 1941: Welded turret Picture: T-34/76 Model 1941 welded turret, from primeportal.net. A close up of the welds on a T-34/76 Model 1941 turret. This is one of the M1941 tanks that had a rectangular transmission hatch. See all the pictures here: http://www.primeportal.net/tanks/dmitry_kiyatkin/t-34_76_1941 T-34/76 Model 1941: Cast turret Picture: T-34/76 Model 1941 with cast turret, from Muzeum Wojska Polskiego, Powiśle, Poland. Early production models were fitted with welded turrets, with later tanks being later fitted with either the welded or a new cast turret of similar shape that was easier and cheaper to produce. Both turrets were provided simultaneously to the T-34 manufacturing plants, with no distinction made between them in Russia at the time. The tank in the picture, a Zavod No 112 origin cast turret variant, had the Polish People’s Army Eagle marking previously painted on turret side. When the main T-34 plant at Kharkov was moved to the Urals starting in August 1941, the tooling for the rolled plate turrets was lost for a while during the evacuation. Thus, the first vehicles produced at the new location were fitted with cast turrets. T-34/76 Model 1941: Quality and Reliability Picture: T-34/76 Model 1941 with welded turret, abandoned at Vinnitsa in western Ukraine after the Dubno-Brody tank battles at the end of June 1941, from Steven Zaloga, T-34/76 Medium Tank 1941-1945. 1994. p. 12. Early models of the T-34, like the M1940 and M1941 were very unreliable. Between the poorly trained crews and general chaos, the tanks weren't built up to the required standards and degraded faster. The V-2 engine's durability standard had gone down to one third of its pre-war maximum mileage, the transmission was poor and the air filters didn't function properly, endangering the crew's life and requiring constant cleaning. Effort to improve the quality wasn't made until 1943. T-34/76 Model 1941/42 STZ: Introduction Picture: T-34/76 Model 1941/42 STZ, from Museé Des Blindés, Saumur, France. The transfer of the Kharkov Locomotive Works to Nizhui Tagil led to more production work for the Stalingrad Tractor Plant (Stalingrad Tractor Zavod - STZ). It was primarily the output of STZ that prevented the production of the T-34 from totally drying up in the trying winter months of 1941-42. Though no complete STZ produced T-34 is known to survive today, some turrets have survived. One is inside the Central Armed Forces Museum in Moscow, another inside the museum on Mamaev Kurgan Hill at Volgograd. T-34/76 Model 1941/42 STZ: A hybrid tank Picture: T-34/76 Model 1941/1942 STZ (this particular one is named Ordzonikidze, after a popular Bolshevik leader from the 1930s) (right) and T-34/76 Model 1941/1942 STZ tanks loaded on trains (left). This variant was a hybrid, with many of the new features developed for the simplified Model 1942, like the new driver's hatch and the improved tow hooks, but old features in the rear area, where the old rounded off hull was retained, as was the rectangular transmission access hatch. They had a turret with a unique chisel fronted gun housing and all steel road wheels. The steel wheels are clearly visible in the left pictures. According to Zaloga, other small differences included an interlocked glacis plate and a modified turret that had a simple flat plate at the rear without the usual rounded corners, to expedite production. Ordzonikidze, in the right picture, had such a rear plate. T-34/76 Model 1941/42 STZ: The plant Picture: T-34/76 Model 1941/1942 STZ tanks sitting in the marshalling yard outside the plant awaiting rail shipment to the front, from o5m6.de. o5m6.de explains pretty well why the modifications on the STZ T-34s were made, and lists Steven Zaloga's "T-34 in action" as its source: The assembly halls in Stalingrad depended heavily on several dozen small contractors for various subassemblies, but many of these factories were in the process of moving eastwards or had already been overrun. Fortunately, several large Stalingrad firms remained and continued to supply STZ. The Red October plant provided armour plates, the Stalingrad Shipyard fabricated the turret and hull and the Barrikady factory initiated production of the F-34 gun. Shortages soon became felt, though. By October, rubber was in short supply and new wheels had to be designed for the T-34 without a rubber rim. Other assemblies, such as the gun, engine and internal layout had to be simplified to cut down on time and material. The weakest point on the welded turret had been found to be the lower chin of the turret front. To reinforce this and at the same time to simplify production, the lower corner was simply cut off and a single flat plate of thicker armour welded in its place. The modified F-34 gun mantlet provided by Barrikady came to a sharp point in contrast to the blunt nose type produced at Zavod Nr. 92 in Gorki. By the fall of 1942, STZ had produced about 3600 T-34s, which amounted to about 40% of the total output of the T-34 to that time. Soon, as the Wehrmacht continued its assault on the city, the assembly halls of STZ would become a battleground. But, by then, the other factories had had time to plant their roots in the Urals and a flood of T-34s would soon be coming to the front. T-34E: More armour! Picture: T-34 Model 1941/1942 STZ "s ekranami" tanks with appliqué armour welded to the hull, rebuilt by Zavod No 27 in Leningrad. Interesting note: A Soviet study showed that APCR shells had a harder time penetrating highly hardened armour than medium hardened armour. However, medium hardness armour resisted AP shells better, whether capped or uncapped. Soviet armour was generally highly hardened, including the appliqué armour. Soviet armoured screens also proved effective against German HEAT. For more details, visit: http://tankarchives.blogspot.ca/2013/05/research-into-soviet-armour-protection.html. Just like the T-26, KV-1 and even BT-5 and BT-7, a lot of T-34s had 15mm thick plates attached to the hull and turret, a response to the rising power of German guns. These were specifically designed to increase protection against lower calibre guns like the Panzer III's 50mm, especially APCR and HEAT shells, but were not very effective against 75mm guns due to overmatching, so as the Germans started fielding more high calibre guns, and didn't have much APCR and HEAT anyway, the T-34Es didn't see large-scale production. Modified STZ T-34s appeared on the Volkhov Front and in Leningrad. These tanks were fitted with added armour plates on the hull front and sometimes on the turret sides and front as well. These were STZ produced machines, but the modification work was done in Leningrad at Repair Zavod No 27. T-34E: More Details! Picture: T-34 with 15 mm of additional armour welded on top of its 45 mm upper front plate, produced by factory #112, from tankarchives.blogspot.ca. Based on the experience in the Winter War, the Red Army decided that the enemy might develop large calibre guns capable of penetrating Soviet tanks. An order was given in the spring of 1941 to increase the front armour of already built and future T-34s to 60 mm. Two tanks with additional armour were developed in July of 1941. These modifications were discontinued when it turned out that the Germans didn't have such guns. In December of 1941, based on news of the Pz. III Ausf. J and its newfound capability to penetrate the front of a T-34 with APCR, it was decided that T-34s should once again be produced with 60 mm of front armour. Due to the low amount of APCR used by the Germans, this modification was discontinued. Three factories produced a number of these up-armoured T-34s in the winter and spring of 1942. STZ built about 200 tanks with improved armour. Factory #112 built 80 hulls and 109 turrets with additional armour. Factory #112 also cast 8 turrets with the sides thickened to 75 mm. Factory #183 also produced a number of these tanks, but no data is available on the exact number. T-34/76: Judging by the turret As mentioned before, the Model 1940 had the shorter L-11 gun mounted low in the mantlet and a rounded turret front. The Model 1941 had the longer F-34 gun mounted high in the mantlet and a rounded turret front. Later models had the F-34 gun and a flat turret front. Summary of the differences Picture: Various T-34/76 turret schematics, from Robert Michulec, T-34 Mythical Weapon. 2007. M1940 * Mounted the L-11 gun. * Had a complex hull. * Used the 10-RT 26E radio set. * Early production had MT-17 gasoline engine instead of V-2 diesel. * The two-man turret had the single, large "pirozhok" hatch, some with a SPKO periscope, others without. * Turret had one periscope on the left. * Had a rectangular transmission access hatch. * First 115 tanks had a ball-mounted machine gun in the rear of the turret. M1941 * Mounted the F-34 gun. * Had a simplified hull and gun mount. * Used the 9-RS radio set. * Used the V-2 diesel engine exclusively. * Same "pirozhok" hatch. * Turret had one periscope on the left and one on the right, but some models only had the one on the left. * Had a circular or rectangular transmission access hatch. * Had more armour on turret roof, sides and rear, and on the hull roof and floor. M1941/1942 STZ * Mounted the F-34 gun. * The hull was a hybrid between the M1941 and M1942. * Used the 9-RS radio set. * Used the V-2 diesel engine exclusively. * Same "pirozhok" hatch. * Turret had one periscope on the left. * Had a rectangular transmission access hatch. Sources Books: * Steven Zaloga, T-34/76 Medium Tank 1941-1945. 1994. * Pavlov Zheltov, Neizvestnyy T-34 (The Unknown T-34). 2001. * Robert Forczyk, Panther Vs T-34: Ukraine 1943. 2007. * Robert Michulec, T-34 Mythical Weapon. 2007. * Anthony Tucker-Jones, T-34 The Red Army's Legendary Medium Tank. 2015. * Steven Zaloga, Armoured Champion: The Top Tanks of World War II. 2015. Internet: * morozovkmdb.com, tanks-encyclopedia.com and tankarchives.blogspot.ca. These are pretty reliable. * wwiivehicles.com, but take everything there with a grain of salt, as it is not very good at interpreting sources. For example: under the armament of a certain tank, the site lists every way the gun was called in the sources, even if it's obviously the same gun. "76.2 mm F-34" is the same thing as "76.2 mm Model 1940, L/41.5" and "76.2 mm L/41" and "76.2 mm L/41 (F-34)", why the heck list all of them?! Also, the T-34-85-I listed on the site is not a real tank. Visit this for more details: http://www.tanks-encyclopedia.com/ww2/soviet/T-34-85-I_Fake_Tanks.php * For great drawings check out o5m6.de and wardrawings.be. * preservedtanks.com, another great site that keeps track of, among others, the last T-34 in the world. * Wikipedia and other small sites (with moderation and a lot of source and double-checking). Big thanks to /u/ExplosiveMachine from Reddit's /r/TankPorn sub that was kind to help me clear up some stuff about the T-34 during my research, as well as everyone else from /r/TankPorn and /r/AskHistorians that helped clear up stuff for me. Special thanks to /u/TheHIV123 for always being there when I had questions, especially back in the days when I barely knew anything about tanks.